Diversity in any crop species is important for the advancement of the species. Cotton diversity has been studied closely by many researchers over the years. The Gossypium species is large and wide-ranging. It has been said, however, that while cotton as a species is diverse, we actually only grow and produce cotton on a narrow germ plasm base.
The following link will direct you to an on-line database for cotton diversity and should represent the latest in mapping and cataloging cotton as a species.
Guide to Selecting a Cotton Variety
Cotton Diversity Database